Optoelectronic devices have been developed for a diversity of applications using a variety of technologies. By optoelectronic devices it is meant both Micro-Electro-Mechanical System (MEMS) devices, and/or semiconductor devices capable of emitting light, such as Light Emitting Diodes (LEDs) or Vertical Cavity Surface Emitting Laser (VCSELs), and photo-sensitive elements capable of receiving light, such as imaging arrays of photodiodes.
Arrays of photo-sensitive elements or photodiodes and VCSELs are often used in, for example, optical navigation systems. Optical navigation systems, such as an optical computer mouse, trackball or touch pad, are well known for inputting data into and interfacing with personal computers and workstations. Such devices allow rapid relocation of a cursor on a monitor, and are useful in many text, database and graphical programs. A user controls the cursor, for example, by moving the mouse over a surface to move the cursor in a direction and over distance proportional to the movement of the mouse. Alternatively, movement of the hand over a stationary device may be used for the same purpose.
VCSELs and arrays of photodiodes are typically formed on a substrate or wafer, using semiconductor fabrication or processing techniques including, for example, deposition, photolithography, and etching procedures. Individual devices are then divided into separate Integrated Circuits (ICs), commonly referred to as a chip or die.
Conventional packaging uses optics either: (i) molded into the IC package; or (ii) as an external component, fixture, or system, mounted on a common circuit board in a fixed position relative to the IC package.
One problem encountered with the first approach, i.e., molding optics into the IC package, is that the optics are limited to a single, external optical surface. Other problems with this approach include limitations on the size and shape of the optics formed directly into the IC package material.
A problem with the second conventional packaging scheme, i.e., externally mounted optics is packaging size. That is, the optics as an external part greatly increases the size or footprint of the electro-optical system. Another problem is that the multiple discrete, external components greatly increase the complexity of the system. Still another problem is reduced stability and reliability. In particular, the multiple component aspect of external parts reduces the mechanical and optical stability of the system, thereby reducing system reliability and increasing potential sources of failure. Potential sources of failure include, for example, misalignment between optics and the optoelectronic device.
Accordingly, there is a need for a packaging structure and packaging method for mounting or attaching an optical component to an IC package of an optoelectronic device that reduces the overall size and complexity of the electro-optical system while enhancing system stability and reliability, and substantially reducing potential sources of failure.
The present invention provides a solution to these and other problems, and offers further advantages over conventional packaging structures and methods of forming the same.